title: The hydrophobic region of the DmsA twin-arginine leader peptide determines specificity with chaperone DmsD.
abstract: The system specific chaperone DmsD plays a role in the maturation of the catalytic subunit of dimethyl sulfoxide (DMSO) reductase, DmsA. Pre-DmsA contains a 45-amino acid twin-arginine leader peptide that is important for targeting and translocation of folded and cofactor-loaded DmsA by the twin-arginine translocase. DmsD has previously been shown to interact with the complete twin-arginine leader peptide of DmsA. In this study, isothermal titration calorimetry was used to investigate the thermodynamics of binding between synthetic peptides composed of different portions of the DmsA leader peptide and DmsD. Only those peptides that included the complete and contiguous hydrophobic region of the DmsA leader sequence were able to bind DmsD with a 1:1 stoichiometry. Each of the peptides that were able to bind DmsD also showed some α-helical structure as indicated by circular dichroism spectroscopy. Differential scanning calorimetry revealed that DmsD gained very little thermal stability upon binding any of the DmsA leader peptides tested. Together, these results suggest that a portion of the hydrophobic region of the DmsA leader peptide determines the specificity of binding and may produce helical properties upon binding to DmsD. Overall, this study demonstrates that the recognition of the DmsA twin-arginine leader sequence by the DmsD chaperone shows unexpected rules and confirms further that the biochemistry of the interaction of the chaperone with their leaders demonstrates differences in their molecular interactions.
authors.affiliation: Department of Biological Sciences, University of Calgary , 2500 University Drive Northwest, Calgary, AB, Canada T2N 1N4.
authors.forename: Tara M L
authors.initials: TM
authors.lastname: Winstone
authors.forename: Vy A
authors.initials: VA
authors.lastname: Tran
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Turner
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D047908:Intracellular Signaling Peptides and Proteins; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021382:Protein Sorting Signals; D055550:Protein Stability; D017433:Protein Structure, Secondary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D002352:Carrier Proteins; C434268:DmsD protein, E coli; D029968:Escherichia coli Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007506:Iron-Sulfur Proteins; D026901:Membrane Transport Proteins; D010446:Peptide Fragments; D011498:Protein Precursors; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C408585:twin-arginine translocase complex, E coli; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase